Many forms of guns have been developed with which to direct or propel a projectile toward a target. Ball throwing devices have been developed which project a ball into a play region, such as a tennis court or batter's box. Such devices are generally complex and are set at predetermined firing rates. Others are trigger operated to fire a single ball or projectile each time the trigger is pulled.
For instance U.S. Pat. Nos. 1,611,814 issued to Buttler; 2,845,055 issued to Collins et al.; 3,009,703 issued to Jentsch et al.; 3,034,785 issued to Graham; 4,185,824 issued to Natwick; and 4,225,140 issued to D'Andrade et al. illustrate shooting devices that use a trigger to fire a projectile each time a trigger is pulled. Butler shows a device wherein the speed of the projectile is controlled by gear driven opposing spindles disposed along the barrel. In each of these devices, the rate of projectile firing is limited to the rate at which individual projectiles can be loaded and the trigger pulled.
Other devices, typically used to practice sport skills, provide for the propelling of balls at regular intervals. Two examples are illustrated in U.S. Pat. Nos. 4,025,071 issued to Hodges; and 4,559,918 issued to Ballerin et al. In these devices, the balls are fed continuously into a pinch roller which projects them to the player. In such devices, there is no control of the rate of ball feed.